Question

Three experiments to investigate the reactivities of three metals are shown.
What is the correct order of reactivity (most reactive least reactive) for these three metals ?

• A. Chromium, Manganese, Nickel
• B. Manganese, Chromium, Nickel
• C. Manganese, Nickel, Chromium
• D. Nickel, Chromium, Manganese

Answer 1

Answer: (B)

Manganese, Chromium, Nickel

Nickle is displaced in two jars from nickel sulfate solution so it is least reactive than both $Mn$ and $Cr$ as metals present on top of the reactivity series can displace metals present below. But in the third jar, $Mn$ is not displaced by $Cr$. So $Mn$ comes on top of the $Cr$ and the correct order of reactivity is $Mn>Cr>Ni$.